Navidea Biopharmaceuticals has developed 99mTc-tilmanocept as a radiopharmaceutical diagnostic imaging agent targeted to the macrophage mannose receptor (CD206) to be used as an aid for lymphatic mapping in cancer surgeries. The United States Food and Drug Administration approved Navidea's new drug application (NDA) for 99mTc-Tilmanocept for use in surgeries to remove melanomas and breast tumors in May of 2013. This SBIR Fast Track application proposes a highly innovative new indication for 99mTc-tilmanocept. Based on ex vivo work with 99mTc-Tilmanocept in Kaposi's sarcoma (KS) lesions from HIV+ (AIDS) patients, Navidea, in collaboration with Drs. McGrath & Maurer of the Univ of California-San Francisco have found th a t a ll KS lesion cells express CD206. KS lesions can occur in the lungs and along the gastrointestinal tract (GI) of AIDS patients where they pose a serious and life threatening risk. Timely and accurate identification of these internal KS lesions is essential for delivery of therapies that may significantly extend the lives of AIDS patients wit KS. Current diagnostic protocols are invasive and challenged to accurately identify internal KS lesions. Our preliminary findings indicated that 99mTc-Tilmanocept could be used to more easily, less invasively and more accurately identify internal KS lesions, thereby improving both the long term outcomes and quality of care for KS patients. 99mTc- Tilmanocept has an extraordinary safety record, with no significant adverse events attributable to 99mTc- tilmanocept having been observed. The primary goal for the proposed efforts is to demonstrate that 99mTc- tilmanocept when injected intravenously can be used as a single-photon emission computed tomography (SPECT) imaging agent for visualization and identification of internal KS lesions in AIDS patients. In addition, despite the very significant progress that has been made over the last two decades in AIDS therapies, KS remains a common, serious and life threatening condition in AIDS patients worldwide. Better therapies for KS are greatly needed. If this project is successful and 99mTc-tilmanocept is demonstrated to bind specifically to cells in KS lesions, follow on studies will be performed (not part of this application) to determine if tilmanocept can be used to target delivery of therapeutics to KS lesions. Targeted delivery of therapeutics may greatly improve their efficacies providing a very significant additional benefit t KS patients. This Fast Track SBIR application proposes preclinical animal studies examining the safety of intravenous injection of 99mTc-tilmanocept (part 1) followed by a clinical study providing the initial evaluation of the safety and efficacy of SPECT imaging studies with 99mTc-tilmanocept to identify internal KS lesions in human patients (part 2).